The Relationship Between Sleep Apnea and Metabolism

Sleep apnea is an increasingly common sleep disorder characterized by intermittent disruptions in breathing during sleep. Obstructive Sleep Apnea (OSA), the most prevalent type of sleep apnea, is characterized by an upper airway obstruction, which reduces the amount of air that reaches the lungs. Morning headaches, daytime mental fogginess, and the characteristic snoring are all symptoms of OSA. Understanding what occurs in the body during an apnea event further reveals the relationship between sleep-disordered breathing and metabolism.

Effects on the Body

The body goes through a variety of changes when it is deprived of sleep. For example, when there is less oxygen intake, as during a sleep apnea episode, there are changes to the body’s metabolism. The Cleveland Clinic defines metabolism as the series of processes your body uses to convert calories and oxygen into energy. Metabolism provides the energy your body needs to perform a wide range of functions, including breathing, digesting food, growing and repairing cells, managing hormone levels, and regulating body temperature. With the fatigue that accompanies sleep apnea, you are less energetic and less active. This slowdown in energy and activity level can lower your metabolic rate, meaning that you can gain weight without consuming any additional calories.

When breathing stops and starts throughout the night, oxygen levels in the blood drop. Our bodies respond by releasing the stress hormone epinephrine. This response elevates the heart rate and can lead to high blood pressure. Overall heart function decreases because it becomes less efficient at pumping blood and because of the pressure changes in the chest. This puts sleep apnea sufferers at higher risk for cardiovascular disease and heart attacks.

Sleep Apnea and Diabetes

For those with undiagnosed or untreated OSA, diabetes is another serious comorbidity. The depletion of blood oxygen levels has a negative effect on blood sugar levels and insulin resistance. For patients with Type 2 diabetes, there is already an inability to regulate the amount of sugar or glucose in the blood. When insulin can’t do its job of getting glucose to the cells where it is used for energy, insulin resistance results. Healthline reports that these changes are not limited to only during the night. Obstructive Sleep Apnea changes how the body responds to insulin and influences glucose levels throughout the day.

Sleep Apnea and Hormonal Changes

There are additional hormonal changes that occur with insufficient sleep. New studies from the Sleep Foundation confirm that lack of sleep results in increased levels of ghrelin, known as the hunger hormone. Along with this hormonal increase comes a decrease in leptin, the fullness hormone. The result is overeating, consuming more calories, and weight gain. Coupled with the natural lack of activity which stems from the overall sleepiness and fatigue from sleep apnea, there is virtually no way to not up in with excess pounds.

Health Comorbidities

Obstructive sleep apnea is also associated with serious health comorbidities, including cardiovascular disease, hypertension, and diabetes. Obesity elevates the risk for these same diseases creating a dangerous mix of critical health conditions.

Metabolic syndrome, a series of cardiovascular risk factors, is also associated with sleep apnea. Its prevalence is highest among patients with obstructive sleep apnea. These risk factors include high blood pressure, high blood sugar, abdominal obesity, and impaired fasting glucose, all of which are highly associated with obstructive sleep apnea and its comorbidities of Type 2 diabetes and cardiovascular disease.

Treatment for OSA

The most immediate treatment for obstructive sleep apnea is Continuous Positive Airway Pressure (CPAP) therapy, which is considered to be the gold standard. All CPAP devices work by pressurizing and filtering air and delivering it through a hose and mask that you wear on your face while sleeping. CPAP keeps airways open and improves breathing quality, leading to improved sleep and better overall health.

One of the first studies to look at the real-time effects of sleep apnea on metabolism and the effectiveness of CPAP was done at Johns Hopkins University School of Medicine. Researchers measured blood sugar, insulin, and cortisol levels throughout the night. The levels were highest in those patients who did not use CPAP, and increased in tandem with the severity of the sleep apnea.

Can Weight Loss Help?

Getting back to a healthy body weight, while not a cure, is a significant first step to easing some sleep apnea symptoms. Research has found that a 10-15% reduction in body weight can reduce the severity of OSA by up to 50%. Weight loss helps reduce the pharyngeal fat in the neck, allowing for less obstructed airways. Reducing abdominal fat helps reduce the compression on the chest wall, facilitating better airflow and less risk of collapsed airways.

Daytime sleepiness and overall fatigue are lessened with weight loss, providing the energy needed for physical activity. Achieving a healthy body weight also helps to reduce the risk of co-morbid health conditions such as high blood pressure, type 2 diabetes, and cardiovascular disease and will help the body’s metabolic functions return to normal.